The present invention relates to a thermal printer including a device for inhibiting heat generation of heating elements existing outside of a width of paper which is supplied.
When printing is achieved by use of a thermal printer including a line head, the contents to be printed (that is, printing data) are developed as a pattern in a given paper width, and in the thermal head heat generating devices existing in a range corresponding to the paper width are selectively heated. However, for printing information developed in a certain paper width, paper having a width narrower than the certain paper width may be supplied in error to the printer. In such case, there is a possibility that even heating elements in a range where the paper is not present actually may be heated. If the heating elements are heated in the absence of paper, then a platen roller disposed opposingly to the heating elements is thermally damaged thereby shortening its life. Also, in the heating elements, when compared with a case in which paper is passing before them, heat is easier to accumulate, thereby resulting in the shortened life of the heating elements.
In a conventional thermal printer, there is employed a structure which does not carry out printing operation when it finds that no paper is supplied. But, the conventional thermal printer does not include a structure which, when the width of the paper is short, can inhibit heat generation of the heating elements of a thermal head that exist outside of the paper width.